Marine propulsion.



N0. 692.,"7. Patented lan. 28, |902.

I. MCK. CHASE.

MARINE PRUPULSION.

(Application led Jan. 29, 1896.)

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No. 692,7. Patented lan. 28, |902.

I. MGK. CHASE.

MARINE PBOPULSION.

` (Application Bled Jan. 29, 1896.)

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ifa/.M JW( 4M UNHED STATES PATENT OFFICE.

ISAAC MCKIM CHASE, OF lVA-SHINGTON, DISTRICT OF COLUMBIA.

MARINE PROPULSION.

SPECIFICATION forming part 0f Letters Patent NQ. 692,117, dated January28, 1902.

Application led January 29, 1896. Serial No. 577,227. (Model.)

To @ZZ whom it may concern:

Be it known that I, ISAAC MCKIM CHASE, a citizen of the United States,residing at Washington, in the District of Columbia, have inventedcertain new and useful Improvements in Marine Propulsion; and I dohereby declare the following to be a full, clear, and exact descriptionof the invention, such as will enable others skilled in the art to whichit appertains to make and use the same.

My present invention relates to the propulsion of marine vessels, hasespecial reference to screw-propellers, with the object of utilizing theenergy of the water displaced by the screw, and consists in certainimprovements in'construction, which will be fully disclosed in thefollowing specification and claims.

In the accompanying drawings, which form part of this specification,Figure l represents a side elevation of my invention applied to avessel; Fig. 2, a rear end view of the inven-` tion detached from thevessel and on an enlarged scale; Fig. 3, a top plan view of the same;Fig. 4, a rear end view of the propeller detached, and Fig. 5 atransverse longitudinal section through one blade of the propeller andone of the guide-blades of the bracket.

A submerged screw-propeller when revolving always discharges the waterupon which it Operates with a more or less rotary motion and frequentlywith considerable velocity. This motion :represents a percentage of theenergy which the engine has developed in giving the propeller motion,and in the prevailing practice this energy is allowed to go to waste inthe course of the water regaining its normal condition. Severalexpedients have been proposed to recover the energy contained in thewater discharged by a screwp'ropeller and to utilize it to augment thethrust. The most promising of these are guide-blades placed aftor behinda screw and upon which the Water impinges when leaving the screw. It hasbeen proposed to apply a number of radiating blades set some distanceaft of the screw and so formed as to receive the obliquely-movin gstreams of water iiowing from the screw and turn them directly astern.It has also been proposed to use a guide-blade in the form of a twistedrudder, the part above the screw curved in' one direction and the partbelow in the Aopposile direction. One of the most successfulapplications of the guide-blade principle is in a device which consistsof a cylinder secured to the vessel. Within the cylinder is a body orboss of such shape that the channel is gradually contracted fromtheforward to the after end. Within the forward part of the cylinderthere are revolvingscrewblades attached to the forward part of the bossand is separate from the after part.

Aft of the revolving blades are numerous guide-blades of contrary oropposite curvature, which are fixed lo the rearward portion of the bossand to the cylinder. The screw is made unusually long, which producesconsiderable rotary motion in the discharged water; but in neither ofthese constructions has the water displaced by the screw been directedimmediately against the guide-blades in such manner as to obtain theenergy of the water in imparting thrust to the vessel. Whileguide-blades are of undoubted utility when properly applied, they havenot been extensively used, owing to difficulties encountered in theirpractical application.

The device hereinafter described is de signed to overcome thedifficulties heretofore found to exist in the application of guidebladesto a screw-propeller and augment the efficiency of the propellingapparatus, especially in its application to twin-screwvessels. Toaccomplish the object of this invention, the bracket-bearing for thepropeller-shaft is placed aft of the screw and is provided withguide-blades, which constitute a part of the bracket and which are soarranged with relation to the screw that they overhang or overlap andenvelop or surround the blades of the screw to about the longitudinalmedian line of the propeller and aft of said line.

' The guide-blades may, howeveri7 be continued IOO object that will bean obstruction to the free ilow of water to a propeller will cause adiminution in its efficiency.

Reference being had to the drawings and the letters thereon, A indicatesa marine vesj sel, and B a screw-propeller of any approved form; C, thepropeller-shaft, which is supported at its forward end in a suitablebearing a and at its after end in a bracket D. The pitch and curvatureof the blades b of the screw may be varied to suit circumstances.

The -bracket D is provided with guideblades c of a diametersubstantially equal to the diameter of the screw and which projectforward beyond the face of the hub cl of the bracketoverhang or overlap,and envelop or surround the propeller to the longitudinal median linethereof, as shown in Figs. l and 3, and the guide-blades are preferablyof a pitch and curvature approximating those of the blades of the screw,but set in a direction opposite thereto, so that the water displaced bythe blades b of the screw (and to which a more or less rotary motion hasbeen imparted) impinges directly upon the blades c ofthe bracket D,imparting the energy contained in the water to the blades of the bracketand thrust to the vessel and also arresting the rotary motion of thewater and restoring it to its normal condition. In the constructionspeedily.

eeail'r side of the stern of a` twin-screw vessel with the `bracket D inits relative position to the screw B; but the guide-blades may beappliedto a single screw by supporting a bracket on the end of the keel of thevessel or upon the stern.

Having thus fully described my invention, what I claim is- 1. Ascrew-propeller, in combination with fixed guide-blades aft of,overhanging, and extending forward to a point within the length of thescrew.

2. A screw-propeller, in combination with fixed vguide-blades aft of,surrounding, extending forward and terminating at approximately thelongitudinal center of the screw.

3. A screw-propeller, in combination with fixed guide-blades aftvof thescrew and Vhaving a pitch and a curve from 'the root to the tip of theblade approximating the pitch and curve of the screw. l

et. A serew-propeller, in combina-tion with fixed guide-blades aft i of,overhanging the screw and approximating the diameter of the screw.

5. A screw-propeller, in combination with a bracket provided withguide-blades, aft of the screw and supporting one end of its shaft.

6. A screw-propeller, in combination with a bracket provided withguide-blades having a pitch approximatingthe pitch of the screw, aft ofand supporting the screw.

7. A screw-propeller, in combination with a bracket provided withguide-blades having transversely-curved or oblique outer surfaces, aftof and adjacent to the screw.

8. A screw-propeller in combination with a bracket provided withguide-blades which surround the screw aft of its longitudinal center.

In testimony whereof I affix my signature in presence of two witnesses.

ISAAC MCKIM CHASE.

Witnesses:

D. C. REINOHL, D. WEIMnR REINOHL.

